This is a multi-center, double-blind crossover study to compare the efficacy of Ultrase MT12 to placebo in the treatment of steaorrhea in Cystic Fibrosis (CF) patients with a history of pancreatic insufficiency. Up to 20 patients will be enrolled at this center, each serving as his/her own control. Each patient enrolled in the study will begin consuming a high-fat diet and will be stabilized on Ultrase MT12, before starting their inpatient stay. The high-fat diet will be adhered to throughout the study and will be appropriate to the patient's weight and size as determined by the investigator. Stools will be collected and analyzed for fat and protein content. The first 6 days the patient will receive either Ultrase MT12 or placebo; for the second 6 days the patient will receive placebo. Patients will be monitored throughout the study for the occurrence of adverse events.